what does the lateral rectus muscle do in the eye

What is the anatomy of the lateral rectus?

Anatomical terms of muscle. The lateral rectus muscle is a muscle on the lateral side of the eyeball in the orbit. It is one of six extraocular muscles that control the movements of the eye. The lateral rectus muscle is responsible for lateral movement of the eyeball, specifically abduction.

How does the lateral rectus move the pupil?

In the orbit of the eye, also called the eye socket, the lateral rectus muscle helps move the pupil away from the body’s midline. The muscle inserts into the temporal (outer) side of the eyeball and stretches to the annulus of Zinn, a tendinous ring circling the optic nerve. This occurs at the apex (back) of the orbit.

What are the extraocular muscles of the eye?

These muscles, along with the superior and inferior oblique muscles, belong to the extraocular muscles of the eye. The lateral rectus muscle arises from the common tendinous ring and runs anteriorly across the lateral part of the orbit to insert at the lateral side of the eyeball.

What is the function of the medial rectus?

Medial rectus muscle (Musculus rectus medialis) Medial rectus is one of the six extraocular muscles located in the orbit. Attaching between the bony walls of the orbit and the eyeball, these muscles serve to synchronously move the eyes.

Where is the lateral rectus muscle and how does it move the eye?

The lateral rectus muscle is a muscle on the lateral side of the eye in the orbit. It is one of six extraocular muscles that control the movements of the eye. The lateral rectus muscle is responsible for lateral movement of the eyeball, specifically abduction.

What is the function of the medial and lateral rectus?

The medial rectus is an adductor, and functions along with the lateral rectus which abducts the eye. These two muscles allow the eyes to move from side to side.

What is the lateral rectus muscle of the eye innervated by?

The abducens nerveThe abducens nerve (cranial nerve VI) exits the brainstem from the pons-medullary junction and innervates the lateral rectus muscle.

What happens when the lateral rectus muscle contracts?

Contraction of the lateral rectus pulls the eye away from the nose (abduction or lateral movement).

How can you distinguish between medial and lateral rectus?

The lateral rectus (LR) is flat muscle located alongside the lateral wall of the orbit. The sixth cranial (abducens) nerve provides innervation of the muscle. The medial rectus (MR) is located alongside the medial wall of the orbit.

What muscles laterally rotate the eyeball?

The lateral rectus, or temple-side, muscles move the eyes outwardly; when they work simultaneously, they diverge, or splay apart, the eyes.

What is the primary function of the lateral rectus muscles quizlet?

The lateral rectus muscle is a muscle in the orbit. It is one of six extraocular muscles that control the movements of the eye (abduction in this case) and the only muscle innervated by the abducens nerve, cranial nerve VI. Its function is to bring the pupil away from the midline of the body.

What controls the movement of the eye?

The brain exerts ultimate control over both voluntary and involuntary eye movement. Three cranial nerves carry signals from the brain to control the extraocular muscles.

Which set of muscles controls the movement of the eye up and down?

The superior rectus is an extraocular muscle that attaches to the top of the eye. It moves the eye upward. The inferior rectus is an extraocular muscle that attaches to the bottom of the eye. It moves the eye downward.

Which eye muscles are involved in focusing the eye for vision?

The ciliary muscle is a circular ring of muscle that attaches all the way around the lens. This ciliary muscle can change the shape of the crystalline lens by stretching it at the edges. It is attached to the lens by zonules (ligament fibres that can be tight or loose).

What is the primary function of the lateral rectus muscles quizlet?

The lateral rectus muscle is a muscle in the orbit. It is one of six extraocular muscles that control the movements of the eye (abduction in this case) and the only muscle innervated by the abducens nerve, cranial nerve VI. Its function is to bring the pupil away from the midline of the body.

How does the medial rectus move the eye?

The superior rectus and inferior oblique muscles primarily move the eye upward. The inferior rectus and superior oblique muscles primarily move the eye downward. The lateral rectus moves the eye horizontally laterally (abduction). The medial rectus muscle moves the eye horizontally medially (adduction).

What does the rectus muscle do?

rectus abdominis – slung between the ribs and the pubic bone at the front of the pelvis. When contracting, this muscle has the characteristic bumps or bulges that are commonly called 'the six pack'. The main function of the rectus abdominis is to move the body between the ribcage and the pelvis.

What is the function of the superior rectus muscle?

The superior rectus has a primary action of elevating the eye, causing the cornea to move superiorly. The superior rectus originates from the annulus of Zinn and courses anteriorly and superiorly over the globe, making an angle of 23 degrees with the visual axis.

Which nerve innervates the lateral rectus muscle?

The abducens nerve innervates the lateral rectus muscle, providing it a neural pathway to the brain. The abducens is also known as the sixth cranial nerve. This nerve innervates some of the other muscles in the eye’s orbit.

What muscle moves the pupil away from the body's midline?

Lateral rectus. In the orbit of the eye, also called the eye socket, the lateral rectus muscle helps move the pupil away from the body’s midline. The muscle inserts into the temporal (outer) side of the eyeball and stretches to the annulus of Zinn, a tendinous ring circling the optic nerve. This occurs at the apex (back) of the orbit.

Can the abducens nerve cause double vision?

Should the abducens nerve cease to function properly, double vision could develop, as the medial rectus would begin to work unopposed. If the lateral rectus muscle itself sustains damage, a person’s eyesight could suffer as a result. However, this is also true if any eye muscles cease to function properly. Last medically reviewed on January 19, ...

Which muscle is responsible for the lateral movement of the eyeball?

The lateral rectus muscle is a muscle on the lateral side of the eyeball in the orbit. It is one of six extraocular muscles that control the movements of the eye. The lateral rectus muscle is responsible for lateral movement of the eyeball, specifically abduction.

What is the lateral rectus?

The lateral rectus is on the right side of the image. Figure showing the mode of innervation of the Recti medialis and lateralis of the eye. The lateral rectus muscle is a muscle on the lateral side of the eyeball in the orbit. It is one of six extraocular muscles that control the movements of the eye. The lateral rectus muscle is responsible ...

What is the disorder of the lateral rectus muscle?

In addition, another disorder associated with the lateral rectus muscle is Duane Syndrome. This syndrome occurs when the sixth cranial nerve which controls the lateral rectus muscle does not develop properly.

Why is my left eye deviated towards the nose?

While attempting to look straight ahead, the left eye will be deviated medially towards the nose due to the unopposed action of the medial rectus of the eye. Proper function of the lateral rectus is tested clinically by asking the patient to look laterally.

Which nerve exits the pontomedullary junction of the brainstem?

These neurons project axons as the abducens nerve which exit from the pontomedullary junction of the brainstem, travels through the cavernous sinus and enter the orbit through the superior orbital fissure. It then enters the medial surface of the lateral rectus to innervate it.

Where does the lateral rectus originate?

The lateral rectus originates at the lateral part of the annulus of Zinn, also known as the annular tendon or common tendinous ring, and inserts into the temporal side of the eyeball.

Can rectus palsy be improved?

Depending on the underlying cause of the lateral rectus palsy, some improvement may occur naturally over time. While the prognosis for a lateral rectus palsy onset by a viral illness is generally positive, the prognosis for an onset of trauma or tumor is quite poor.

What is the function of the lateral rectus?

Lateral Rectus. The lateral rectus is a muscle of the eye’s orbit. The main function of this muscle is to pull the pupil away from the midline of the body. The word lateral rectus comes from the Latin latus, meaning “side” and rectus, “straight.”.

Which muscle is on the upper medial side of the eye?

The superior oblique muscle is on the upper medial side of the eye. That means it is closer to the nose. The primary job of this muscle is to turn the eye inward. Every eye muscle does multiple jobs, so the superior oblique does contribute to other motions.

What is the largest muscle in the eye?

This muscle shares an origin with several other extrinsic eye muscles, the anulus tendineus, or common tendon. It is the largest of the extraocular muscles and its only action is adduction of the eyeball.” (Wikipedia)

What are the four recti muscles?

The four recti muscles are the lateral rectus, the medial rectus, the inferior rectus, and the superior rectus while the two oblique muscles are the inferior oblique and the superior oblique. In this post, we’ll talk about each of the six muscles and discover their function and purpose in the human eye.

Which muscle is capable of depressing the pupil?

Here are more details of the inferior rectus muscle: “ [The inferior rectus muscle] depresses, adducts, and helps extort (rotate laterally) the eye. The inferior rectus muscle is the only muscle that is capable of depressing the pupil when it is in a fully abducted position.” (Wikipedia)

Where does the lateral rectus originate?

Here is more in-depth information on the lateral rectus muscle: “The lateral rectus originates at the lateral part of the annulus of Zinn, also known as the annular tendon or common tendinous ring, and inserts into the temporal side of the eyeball. The annulus of Zinn is a tendinous ring that surrounds the optic nerve and serves as ...

Where does the word "medial rectus" come from?

The word medial rectus comes from the Latin medius, “middle.”. Discover more about the medial rectus here: “As with most of the muscles of the orbit, it is innervated by the inferior division of the oculomotor nerve (Cranial Nerve III). This muscle shares an origin with several other extrinsic eye muscles, the anulus tendineus, or common tendon.

What is the action of the lateral rectus?

Action. The action of the lateral rectus is to abduct the eye (see figure 1) 1. Unlike most of the other extraocular muscles, it has no significant contribution to movement in the other ocular axes.

Where is the lateral rectus?

Lateral rectus runs anteriorly on the medial surface of the eye and inserts into the lateral surface of the sclera just posterior to the junction of cornea and sclera 2.

What does the rectus mean?

Rectus comes from the Latin rectos, meaning straight 1. oculomotor nerve palsy. as the lateral rectus and superior oblique muscles are the only extraocular muscles not supplied by the oculomotor nerve, the unopposed force generated by these muscles results in depression and abduction of the affected eye. abducens nerve palsy.

Which nerve supplies the rectus?

Lateral rectus is unique among the extraocular muscles in being supplied by the abducens nerve.

Where does the word "rectus" come from?

Rectus comes from the Latin rectos, meaning straight 1.

Which muscle is responsible for abduction?

The lateral rectus muscle is one of the six extraocular muscles that control eye movements. It is responsible for abduction and is the only muscle that is innervated by the abducens nerve (CN VI).

What Is Sixth Nerve Palsy?

Sixth nerve palsy is also known as lateral rectus palsy. Palsy is a type of full or partial paralysis.

What Are the Causes of Sixth Nerve Palsy?

There are several different causes of sixth nerve palsy. It may be present at birth, it may be caused by physical trauma, or it may be a result of a medical condition. In some cases, the cause is unknown.

What Are the Symptoms of Sixth Nerve Palsy?

Symptoms of sixth nerve palsy vary from person to person, depending on the cause. One of the main symptoms is eye alignment. Your eye can’t turn fully outward. When you look straight ahead, your eye may turn inward. You may experience double vision when you look in the direction of your affected eye.

How Is Sixth Nerve Palsy Diagnosed?

Sixth nerve palsy is diagnosed through several tests, including a neurological exam that involves different tests and questions used to check the functions of your nerves.

What Is the Treatment for Sixth Nerve Palsy?

For some people, treatment may not be needed, and the condition may disappear on its own within two months.

Which muscles control the eye movement?

Three antagonistic pairs of muscles control eye movements: the lateral and medial rectus muscles, the superior and inferior rectus muscles, and the superior and inferior oblique muscles.

Which muscles are involved in vertical and horizontal eye movements?

The contributions of the six extraocular muscles to vertical and horizontal eye movements. Horizontal movements are mediated by the medial and lateral rectus muscles, while vertical movements are mediated by the superior and inferior rectus and the superior (more...) The extraocular muscles are innervated by lower motorneurons ...

What are the three antagonistic pairs of muscles that control the eye?

Three antagonistic pairs of muscles control eye movements: the lateraland medialrectus muscles, the superiorand inferior rectus muscles, and the superiorand inferior oblique muscles. These muscles are responsible for movements of the eye along three different axes: horizontal, ...

What muscles are responsible for elevation?

Elevation is due to the action of the superior rectus and inferior oblique muscles, while depression is due to the action of the inferior rectus and superior oblique muscles. When the eye is abducted, the rectus muscles are the prime vertical movers.

Which nucleus innervates the superior oblique muscle?

The abducens nucleus innervates the lateral rectus muscle; the trochlear nucleus innervates the superior oblique muscle; (more...) In addition to supplying the extraocular muscles, a distinct cell group within the oculomotor nucleus innervates the levator muscles of the eyelid; the axons from these neurons also travel in the third nerve.

Which cranial nerve innervates the extraocular muscle?

The abducens nerve(cranial nerve VI) exits the brainstemfrom the pons-medullary junction and innervates the lateral rectus muscle.

Which nerve is responsible for the innervation of the extraocular muscles?

The oculomotor nerve (III), which exits from the rostralmidbrain near the cerebral peduncle, supplies all the rest of the extraocular muscles. Although the oculomotor nerve governs several different muscles, each receives its innervationfrom a separate group of lower motor neurons within the third nerve nucleus.

Which muscle is responsible for allowing the eye to focus on objects?

This type of opthalmoplegia may affect any of the following three internal muscles of the eye: Ciliary muscle . A ring of muscle that affects the shape of the lens. This enables the eye to focus on nearby or far away objects. Dilator pupillae. A muscle that largens the size of the pupil to let in more light.

Which muscle moves the eye up and down?

These muscles enable the eye to move up, down, side to side, and roll in a circle. This type of ophthalmol may affect any of the following six extraocular muscles: Superior rectus. A muscle fixed to the top of the eye that moves the eye upward. Inferior rectus.

What is the term for the weakness of the eye muscles?

What is Ophthalmoplegia (Weak Eye Muscles)? Ophthalmoplegia refers to the weakness or paralysis of the eye muscles. The condition can affect one or more of the six muscles that keep the eye in place and control its movement. This can lead to eye movement abnormalities.

What is the term for the area of the brain that is affected by MS?

The term internuclear refers to the area of the brain affected. It is an area that works as a pathway between the nuclei. These are two clusters of nerve cells in the brain. Around 23 percent of MS patients have internuclear ophthalmoplegia. Other conditions that may result in internuclear ophthalmoplegia include:

Can you have double vision in one eye?

If the right eye is affected, the individual will have double vision when looking to the left. This type of ophthalmoplegia may develop in one eye (unilateral internuclear ophthalmoplegia) or both eyes (bilateral internuclear ophthalmoplegia).

Where does the muscle go in the eye?

The muscle courses anteriorly, sliding over the medial part of the eye to cross its equator and reach the anterior half of the eyeball. It then inserts onto the medial side of the eyeball, around 5 millimeters posterior to corneoscleral junction.

What is the function of the medial rectus muscle?

Function. When contracting, each medial rectus muscle adducts the eyeball, i.e. pulls the eye medially. This action is important in two types of ocular movements; conjugate and disconjugate. Conjugate movements are when both eyeballs move in the same direction.

What is the movement of the eyeballs that converge toward the midline?

Disconjugate movements are when the eyeballs converge or diverge from the midline. When both medial recti contract, they converge the eyeballs toward the midline. Convergence is a part of the accommodation reflex, when the eyes adjust to observe a close object.

Why is the medial rectus muscle weak?

Weakness of the medial rectus muscle can happen for five reasons; Oculomotor nerve palsy and/ or oculomotor nucleus injury (e.g. cavernous sinus thrombosis or cerebral infarction)

What is the medial rectus?

Medial rectus is one of the six extraocular muscles located in the orbit. Attaching between the bony walls of the orbit and the eyeball, these muscles serve to synchronously move the eyes. Besides medial rectus, this group of muscles also gathers the superior rectus , inferior rectus, lateral rectus, superior oblique and inferior oblique muscles.

What are the symptoms of medial rectus palsy?

thyroid ophthalmopathy as part of Graves disease) Typical signs and symptoms of medial rectus palsy are divergent strabismus and consequential diplopia. Treatment is based on discovering the cause of the palsy and treating it.

What causes the eye to move away from its primary position?

Weakness of any of the extraocular muscles causes the affected eye to move away from it’s primary position, under the influence of a healthy antagonistic muscle. So damage to the medial rectus muscle would affect the normal position of the eyes by diverging the affected eye toward the pull of lateral rectus muscle, i.e. the eye would move laterally.

Overview

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